LED notification in blackberry

The LED light on the top of your BlackBerry ® device flashes different colors to indicate different states.

Green    :  You are in a wireless coverage area.

Blue      :     Your device is connected to a Bluetooth® enabled device.

Red      :     A new message has arrived and your selected notification profile is set to notify you using the LED. If you are using your device with a smart card, your device is accessing data on the smart card.

Amber : The battery power level for your device is low.